<!DOCTYPE html>
    <html>
        <body>
            <p>点击下面的按钮来显示今天是周几：</p>
            <button onclick="myFunction()">点击这里</button>
            <p id="demo"></p>
            <script>
             function myFunction(){
                var x;
                var d=new Date().getDaY;
                switch (d){
                    case 0:
                    x="Today it's Sunday";
                    break;
                    case 1:
                    x="Today it's Monday";
                    break;
                    case 3:
                    x="Today it's Wednesday";
                    break;
                    case 4:
                    x="Today it's Thursday";
                    break;
                    case 5:
                    x="Today it's Friday";
                    break;
                    case 6:
                    x="Today it's Saturday";
                    break;
                }
                document.getElementById("demo").innerHTML=x;
            }
            </script>
        </body>
    </html>